Abstract

PIP: This review describes the research done so far on sperm enzyme inhibitors to establish their potential as contraceptives. The mode of action of hyaluronidase inhibitors is discussed, a chronological summary of studies showing the in vivo and antifertility activity of synthetic hyaluronidase is provided, present research needs are indicated, and marketed compounds able to inhibit hyaluronidase are identified. The mode of action of acrosin inhibitors, advantages and shortcomings of different acrosin-inhibiting agents and certain ions, and potential utility of acrosin inhibitors in enhancing the contraceptive potency and reducing the side effects of the IUD, and the systemic application of acrosin inhibitors to induce infertility are discussed. Possible use of gossypol as a spermicide, the effect of gossypol on the fertilizing capacity of human spermatozoa, and its possible use as a vaginal contraceptive are assessed. Theoretical and practical implications of using a form of the enzyme lactate dehydrogenase found only in the male genital tract as an antigen for contraceptive purposes are discussed. Other enzymes whose inhibitors would also lead to infertility, giving promise of contraceptive applications, are identified. The author concludes that inhibitors of sperm enzymes, whether chemical agents or antibodies, could be potent contraceptives whose use is attractive because enzymes are often sperm specific. A sperm directed contraceptive method would probably be more feasible in the female, because the concentration of the inhibitors needed to induce contraception is less and the inhibitors can be applied locally in the female. Research to date has focused on only a small number of the possible enzymes that could be inhibited to prevent fertility, primarily because too little is known about the biochemical properties of the sperm enzymes and their role in fertility.